Hitherto, there has been a related art tandem type image forming apparatus having structure where a plurality of image forming unit for forming images having different colors (for example, yellow, magenta, cyan, and black) are arranged in series along a conveying path of a recording medium. In this related art, a frame structure where an upper frame is mounted on a lower frame, and the rigidity of the lower frame is lower than the rigidity of the upper frame.
If the frame structure of the related art is employed, the lower frame having low rigidity may be twisted or distorted as a biased load is applied to the frame structure of the image forming apparatus due to the difference in level and the inclination at a position where the apparatus is disposed. Therefore, even though the rigidity of the entire of the frame structure is not increased, it may be possible to suppress the generation of the twisting or distortion at the upper frame having high rigidity and to maintain high accuracy in the relative positional relationship between a plurality of image forming unit assembled with the upper frame. Further, since the rigidity of the entire frame structure does not need to be increased, it may be possible to suppress the increase in the weight of the entire frame structure.
Further, in the image forming apparatus of the related art, a recording medium cassette for storing recording media or feed unit for feeding a recording medium to the image forming unit (four sets of image forming units) are mounted on the lower frame. In order to supply recording media to the recording medium cassette, the recording medium cassette is generally formed so as to be drawn or separated from an apparatus body. As a specific example of this structure, there is a structure where a recording medium cassette slides along a guide mechanism.